Set ui::KeyEvent::key_ (DOM Level 3 key) under X11.

ui/events/keycodes/keyboard_code_conversion_xkb.h

+// Copyright (c) 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef UI_EVENTS_KEYCODES_KEYBOARD_CODE_CONVERSION_XKB_H_
+#define UI_EVENTS_KEYCODES_KEYBOARD_CODE_CONVERSION_XKB_H_
+
+// These functions are used by X11 targets and by Ozone/XKBcommon targets.
+
+#include "base/strings/string16.h"
+#include "ui/events/keycodes/xkb_keysym.h"
+
+namespace ui {
+
+enum class DomKey;
+
+// Returns the DomKey associated with a non-character xkb_keysym_t.
+// Returns DomKey::NONE for unrecognized keysyms, which includes
+// all printable characters.
+DomKey NonPrintableXkbKeySymToDomKey(xkb_keysym_t keysym);
+
+// TODO(kpschoedel) crbug.com/442757
+// Returns the dead key combining character associated with an xkb_keysym_t,
+// or 0 if the keysym is not recognized.
+// base::char16 DeadXkbKeySymToCombiningCharacter(xkb_keysym_t keysym);
+
+// Return the DomKey determined by the XKB layout result (keysym, character).
+DomKey XkbKeySymToDomKey(xkb_keysym_t keysym, base::char16 character);

[Wez, 2015/05/06 23:51:53]

Consider clarifying that these functions must never be called, directly or
indirectly, from within any sandboxed process; they should only ever be used by
the Browser process, since they need to call out to X11.

You've called this XkbKeySymToDomKey; AFAIK there's no difference between
xkb_keysym_t and stock X11 KeySyms, so the fact that this API uses XKB APIs
internally is really just an implementation detail - in which case I'd suggest
renaming to just XKeySymToDomKey() - WDYT?

[kpschoedel, 2015/05/07 16:21:33]

These don't — they're just direct maps.
Done.

+
+}  // namespace ui
+
+#endif  // UI_EVENTS_KEYCODES_KEYBOARD_CODE_CONVERSION_XKB_H_
+